US957741A - Motor-starter. - Google Patents

Description

A. J. BURNS. MOTOR STARTER. APPLICATION FILED FEB. 13, 1909.

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witness A. J. BURNS.

MOTOR STARTER.

APPLIUATION FILED 1 1113.13, 1909.

Patented May 10, 1910.

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MOTOR STARTER.

APPLICATION FILED FEB. 13, 1909.

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Patented May 10, 1910.

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A. LBURNS.

MOTOR STARTER.

I APPLICATION FILED FEB.13, 1909. 957,741 Patented May 10,1910.

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witnmoo A. J. BURNS. MOTOR STARTER. APPLICATION FILED FEB. 13, 1909. 957,741 Patented May 10; 1910.

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UN 1 TED STATES PATENT OFFICE.

ANTHONY J. BURNS, OF HEGEWISCH, ILLINOIS, ASSIGNOB 0F ONE-HALF T0 EDWARD OF CHICAGO, ILLINOIS.

MOTOBrS'IABTEE Specification of Letters Patent.

Patented May 10, 1910.

tage and overload-release type whereby the motor is cut out of circuit with the source of current whenever the main line is opened or the circuit interrupted, or when the flow of current becomes excessive.

The invention has for one of its objects to provide a motor starter of this character which is of comparatively simple and inexpensive construction,thoroughly reliable and efiicient in use, and so designed as to be readily manipulated. Another ect of he invention is the provision of means whereby the resistance or impedance is cut out of circuit in a step by step manner, with a certain time element introduced between each step for preventing the operator from too uickly throwing on the full voltage before t e motor has an opportunity to reach its normal speed.

A further object is the employment of an improved lock-out device for olding the operating handle of the motor starter in oil position as long as the main line circuit is 0 en and no current flowing from the suppry station so as to revent the operator om leaving the hand e in runnin position I with the motor connected across-t e supply y a circuit, and subject to be burned out full rush of current when the main circuit is closed.

An additional object is to rovide an imroved means for releasing t e biased hanle of the motor starter under no-voltage'or overload condition of the system.

With these objects in view and others, as

will appear as the description proceeds, the mventioncomprises the various novel features of construction and arrangement of parts which will be more'fullydescribed ereinafterand set forth with particularity in the claims appended hereto.

diment of the invention,

v with tact with journals} that are mounted in bearing lugs 5 de ending from the middle section '2 at the rent and rear-thereof and on the -10 in the ortions broken away and in section for i1 ustrating the arrangement of the various parts and details of construction. Fig. 2 1s a central vertical section of a mo tor starter with some of the, circuit connections shown in diagram. Fig. 3 is a horizontal section. Fi 4 is a transverse section on line H, Fig. 2. Fig. 5 is a perspective view of the automatic releasing latch for the handle and step device therefor. Fi 6 to 10 inclusive, are detail sectional views showing the various positions of the device for controlling the step by step movement of the handle. Fig. 11 is a diagrammatic view of the circuit connections.

Similar reference characters are employed to designate corresponding parts throughout the views.

In the present instance, I haveelected' to illustrate the invention as applied to a motor starter for alternatin current motors but it is to be understoo that it ma be used for other motors by substitutin 0 io resistance for reduction coils, and urthermore, other certain features of the apparatus which can be used for other. devices than motor starters.

Referring to the drawin A designates a casing or the apparatus w ich is composed of sections 1, 2 and 3, that are divisible horizontally, the bottom section 3 serving to form a reservoir for holding oil in which the various circuit connections are made and broken during the operation of the starter and on the middle section 2 are supported all the various parts of the startin mechanism the cover 1 being removable or afiording access for the (purpose of inspection or repair. -On the mi dle section 2 of the easing are brackets 2 projecting from therear thereof designed to receive bolts or other fastenin means whereby the casing can be mounte on the panel of a switch-board.

.Dis osed. in the bottom section 3 is a conrum B which has its ends provided front journal is a toothed wheel or gear 6 that meshes with a toothed sector 7 on the shaft 8 of the operating handle 9, the said c section shaft bein 'journaled in a bearinfi opening e mid 2 whereby the drum is oscillated by the swinging movement of the handle. Disposed above the drum and at opposite sides thereof are slabs of marble 11 bolted to internal lugs 12 formed on the middle section of the casing. These slabs support the contact fingers 13 which bear on the periphery of the drum to control the electrical con nections of the motor. The fingers 13 are attached to terminals 14 bolted on the slabs of marble and to which the ends of the conductors leading to the impedance and resistance coil, motor and line wires, are connected. Each finger 13 is connected with its terminal piece 14 by a spring 15, Fig. 1, which is adjustable for varying the tension of the finger on the drum. The spring has one end rigidly secured to the terminal piece 14 while the finger is connected with the other end, and passing through the contact finger and spring is a screw 16 that bears against an abutment 17 formed on the terminal piece so that by adjusting the screw, the wiping part 18 of the contact finger can be set with respect to the drum to effect the desired contact with the drum. A set of contact fingers on one slab is arranged to bear on the drum at a point directly opposite the other set and the drum is provided with a set of contacts 19 for each group of contact fingers, and the contacts of one set are cross-connected with those of the other set, the contacts being arranged in three positions so that the drum requires a movement of three steps in throwing the apparatus from off to running position. Also mounted on the insulating slabs 11 are terminal pieces 20 that carry resilient metal brushes 21 which are adapted to bear on contact bars 22 on the. drum when the latter is in full running position to provide an auxiliary path for the current when the motor is connected'directly in line circuit. Disposed in. the middle and cover sections are the impedance coils G, of any suitable construction, and provided with iron cores or shells 23 which have their ends supported in brackets 24; on the middle section, as shown in Fig. 3, and the various windings of these coils are connected with the terminal pieces of the appropriate contact fingers for the controlling drum.

The operating handle 9 is biased to off position by a coil spring 25 which has its outer end 26 pinned or otherwise suitably secured to the casing A and its inner end 27 fastened to the handle shaft 8, and over the spring and disposed between the casing A and handle is a housing 28. The handle is held in running position by a locking latch 29 that is disposed at the front of the casing A and is mounted on a rock-shaft 30 that extends into the casing for connection with the no-voltage and overload-release device, the latch being provided with a notch 31 which receives a roller 32 mounted in a yoke 33 on the rear side of the operating handle 9. This latch, which is held in locking position by gravity, has its outer end beveled at 34 so as to be raised by contact with the roller as the handle is moved to running position so that the notch of the latch can engage the roller catch on the handle. This latch is adapted to be released by a weight or hammer 35 mounted to swing on the inner end of the rock-shaft 30 of the latch and said hammer is provided with a rearwardlyextending projection 36 that is adapted to strike an approximately horizontal arm 37 rigidly secured to the rear end of the latch shaft 30, the hammer being in raised position when set so as to acquire considerable force before reaching the latch arm 27 to impart a blow thereto to effectively release the latch from the operating handle under emergency conditions so that the handle can be thrown to oil? position by its spring. The arm 37 is confined between spaced steps 38 and 39 disposed one above the other and the latch is so weighted with respect to the arm 37 as to maintain the latter normally against the upper stop 38, and when the hammer strikes the arm 37, the lower stop 39 limits the unlatching movement. The hammer or latch-releasing member 35 is held set or in raised position by a no-voltage release electro-magnet 40 which is mounted on a vertical supporting plate 11 secured to side brackets 42 formed on the middle section 2 of the casing. As long as the current flows through the windings of the electro-magnet 40, the hammer will be maintained in such position and as soon as the windings become eenergized by the cessation of the flow of current, the hammer will descend and strike the latch arm 37 and release the operating handle so that it will return to oif position. The windings of the electro-magnet 10 are connected across the supply circuit at a point between the source of current and motor controller so that the electro-magnet will respond immediately to any flow of current in the supply circuit and the circuit of the electro-magnet 40 is controlled by electro-magnetically actuated overload switches I) that are mounted on the supporting plate d1. Normally, the switches D are closed and adapted to be opened only under overload conditions so as to permit the latch-operating device to release the latch and open the motor circuit by the return of the controlling drum to off position.

Each switch D consists of a U-shaped armature 43 that has its side members disposed in the spools of the magnet coils 44, and this armature is held in operative position in yoke-shaped supports 45 on the lower ends of the magnet spools. Extending into the upper ends of the magnets 44 is a U-shaped as shown in Fig. 6, and as the hand iron yoke 46 mounted in a bracket 47 and adjusted by a screw 48 so as to vary the position of the yoke and conse uently the set of theelectro-magnets, acco ing to the overload voltage at which the switch is adapted to open. The windings of the electro-magnets of the Y overload switches are connected directly across the circuit when the starter is in running position. Extending across each armature 43 is a hinged contact member 49, Fig. 2, thatengages a fixed contact on the supporting plate 41 and whenthe armature is in lowered position, the parts 49 and 50 are in contact so as to maintain the circuit of the controlling magnet 40 closed. The contact lever 49 is mounted on an L-shaped bracket 51 on the supporting plate 41 and this bracket and the contact 50 are connected by wires 52 and 53 with the windings of the controlling magnet 40. When the armatures 43 are raised by overload current, the switches D will open and cutthe electro-magnet 40 out of circuit.

In order to arrest the movement of the handle 9 as it is thrown to 011' position, a cushioning device E is provided within the middle section 2 of the casing A at the front thereof, said device consisting of a cylinder 54 in which works a piston 55 that has a rod 56 that is provided with a head 57 so located that the toothed sector 7 will strike the head before the operating lever reaches the end of its movement and force the piston inwardly to compress the air in the cylinder and thereby cushion the handle and gradually bring it to rest.

A retard or checking device is provided whereby the operator is prevented from throwing the operating handle 9 to running position too rapidly so that the motor can be gradually brought up to speed before the full position voltage is impressed on the motor windings. Connected with the toothed sector 7 is a radially-projecting member 58 that has an arcuate arm 59 disposed concentrically around the handle shaft 8 and extending over the latch shaft 30. This arm 59 has two forwardly-projecting teeth 60 and 61 and two rearwardly-projecting teeth 62 and 63. The shaft 30 is-journaled in a fixed sleeve 64 fastened to the casing and on this sleeve is a pivoted weight 65 that has front and rear fingers 66 and 67 that coiiperate, respectively, with the front and rear. teeth of the arcuate arm 59 for controlling the movement of the operating handle 9 so that the latter can be moved only in a step by step manner. During the initial art of the movementof the handle from 0% position, the extreme front tooth 60 of the arm 59 is brought into engagement with the forward finger 66 of the swinging weight 65,

e continues its movement, the arm 59 will tiltthe weight to the position shown in Fig. 7, when the latter projecting fin r 67 will engage the front rear tooth 62 o the arm 59. The arm '59 will be prevented from further forward movement by the eccentric part of the weight striking the bottom of the arm 59, and when this point is reached, the operating handle has moved one step and caused the controlling drum B to connect the motor in circuit with the full resistance on impedance.

In order to move the operating handle anhandle a slight distancein order to disengage the finger 67 from the projection 62 and thereby allow the weight 65 to return to normal position, as shown in Fi 8, with the finger 66 disposed in front of the second front tooth 61. The handle can now be moved another step to the position shown in Fig. 9. The rear finger 67 will thus be brought into engagement with the second rear tooth 63 which prevents further" forward movement of the handle, as explained in connection with Fig. 7. By this time, the controlling drum has been moved another step so as to cut out part of the resistance or impedance.

To move the operating handle to third position, the handle is first returned far enough to permit the finger 67 to be released from the tooth 63, whereupon the weight drops to the position shown in Fig. 10. The operating handle can then be moved forwardly without further hindrance since there are no more front teeth on the arm 59 for throwing the weight to locking position. By thus introducing a time element between each step in the movement of the operating handle, the motor has a chance to come up to speed before the full voltage of the supply circuit is impressed on the motor. When, the handle 9 returns to off osition, the weight 65 does not interfere since the front teeth 60 and 61 of the arm 59 will ride freely over the finger 66 of the weight. Mounted on the sleeve 64 is a second pivoted swinging weight 68 which-is adapted to return the hammer 35 to raised position after the same has dropped to release the handleholding latch and this weight is moved to inoperative position with respect to the hamaner. and held in such position as long as the operating handle is in full running position, so that the hammer will be free to drop under emergency conditions.

On the weight 68 is a projection 69 which is engaged by a rearwardly-extending lug 70 on the-arcuate arm 59 for raising the weight and holding the same raised when the parts are in running position, as shown in Figs. 5 and 10. On the weight is an L-shaped projection 71 disposed in the path of the hammer 35, so that when the latter drops, it

will rest on the projection 71 and the weight can restore the hammer to normal position,

other step, it is first necessary to return the &

as shown in Fig. 6, as soon as the arm 59 returns during the return of the operating handle 9 to off position. A. lock-out means is employed for locking the operating handle in off position, so that the operator will be prevented from manipulating the motor starter as long as the supply circuit is idle. This lock-out device comprises a detent 72 that is mounted on a pivot 73 on the supporting plate 41 and connected with an upwardly-projecting lever 74 which has an armature 75 disposed adjacent the ends of the cores of the electro-magnet 40 opposite from those operating on the hammer 35, so that the electro-magnet 40 controls both the 110-voltage releasing device and the lock-out means. On the detent 72 is a forwardlyprojecting member 76 that is adapted to engage in a notch 77 in the arm 59 when the latter is in initial position, and when the electro-magnet 40 is deenergized, the detent will thus prevent the handle 9 from being actuated. On the supporting plate 41 is a cut-out switch F, Fig. 1, that consists of a spring contact 78 mounted on the post 79 and adapted to engage a contact point 80, the spring contact and contact point being connected in circuit with the electro-magnet- 40 so that the latter will be cut out of circuit when the switch F is opened. On the spring contact 78 is an insulating piece 81 against which the arm 58 strikes as the handle is thrown to ofl position so as to thereby open the switch F. The switch F is adapted to close during the initial movement of the handle 9 so that the electro-magnet 40 will be connected in circuit with the source of current at the power station and become energized if the supply circuit is in operating condition so that the detent 72 will be immediately released to enable the operator to manipulate the motor starter. It will thus be seen that the lock-out device cannot be unlocked unless the supply circuitis closed and current flowing so that the motor-starting apparatus is primarily under the control of the engineer at the central power house.

The locking latch f6? holding the lever or handle 9 in running position can be manually released at any time by pressing a push button 82, Fig. 2, arranged in the upper end of the handle and provided with a stem 83 extending longitudinally of the handle and connected by a link 84 with the lever 85, said lever being fulcrumed at 86 and formed with a rearwardly-projectingmember 87 that is disposed under the latch so as to raise the same out of engagement with the roller 32 when the push button is depressed against the tension of the spring 88.

From the foregoing description, it will be observed that the apparatus shown is designed for a two-phase motor but it is to be understood that it may be adapted for systems of any other number of phases.

earner Referring to the diagram shown in Fig. 11, Gr designates an alternating current generator of the two-phase type having rings a, a for one phase and rings 6, b for the other phase and these are connected, respectively, with the windings 'w, 'w of the twophase motor M through the motor starter. When the drum of the motor starter is in first position, the current flows through the path consisting of the ring a, wire 0, contact d, drum segment 6, contact f, contact finger d, impedance coil 1, contact finger d contact g, contact h, contact finger d wire 2', motor winding w, wire 7', contact finger a3", drum contact 70, drum segment 6, contact finger m, wire m, and the other generator ring a. At the same time the current passes through the wires 0 and 0' of the circuit in which the overload switches D and cut-out switch F and elect-ro-magnet 40 are included. When the drum is in the second position, the current flows through the path consisting of the ring a, wire 0, contact finger (11, contact 6, contact p, contact finger d,

inductance I, contact fingers 9, contact 7", contact 8, terminal finger d wire 2', motor winding w, wire 7', contact finger (1, contact If, and drum segment 6, contact finger m, wire m, and ring a. When the drum is turned to the full running position, the current flows through a path consisting of the ring a, wire 0, contact finger d and contact brush at, contact bar 4;, contact finger and brush d and u, wire :19, windings 44 of one of the overload magnets, winding 'w of the motor, wire 7', contact finger a? and contact brush 10 bar '0', contact finger m, and contact brush u, wire m, and ring a of the generator. It will thus be seen that when the drum is in its third position, the impedance or resistance is entirely cut out and the winding of the overload magnet is connected in series with the motor. The various circuit connections for the other phase of the motor are substantially the same for the phase that has just been described so that urther explanation is deemed unnecessary. From the foregoing description, taken in connection with the accompanying drawings, the advantages of the construction and of the method of operation will be readily apparent to those skilled in the art to which the invention appertains, and while I have described the principle of operation ofthe invention, together with the apparatus which I now consi er to be the best embodiment thereof, I desire to have it understood that the apparatus shown is merely illustrative, and that such changes may be made when desired as are within the scope of the claims appended hereto.

Having thus described the invention, What I claim is 1. A device of the class described comprising a controlling handle, means respona to abnormal conditions for releasably.

holding the handle in position, a lockout means for holding e handle 'in off position, a switch held open by the handle when the latter is in oil gasitlon, and a circuit controlled by the switc for releasing the look-out means during the initial'movement of the handle from off position.

2. A device of the classdescribed comprising a lever for controlling the circuit connections, a latch for lockin the same in running position, a weight a apted to re lease the latch, an electro-ina et for bold ing'the weight in'raised position, and a second weight arranged to restore the firstmentioned weight after releasin the latch.

3. A device of the class described comprisin an operating lever, a locking device for he ding the same in running position, a. pivoted weight for releasing the latch, a second pivoted weight for restoring the first-mentioned weig t, and an electro-magnet for holding the releasing weight in normal position. 1

4. A device of the class described com risby 1 ing a controlling lever, a latch hel gravity in locking position, an armature constituting a weight arranged to release the 5 latch by a hammer blow, electrical means for holding the armature in set position, and manna ly operable means on the lever for releasing the latch.

5. A device of the class described comprising a controlling lever, a gravity-set latch for holding the" same in running position,

an electro-magnet responsive to overload or no-voltage conditions and provided with an i armature arranged to drop when the electro- I magnet is denergized for imparting a hamease the latch, means for j mer. blow to re automaticall restorin operative re ation wit the electro-ma ct, and manually operable means on the ever for releasing the latch.

' 6-. A device of the class described comprising an operating lever, a latch for holding 1 the same in running position, a weight for releasing the latch, electrical means for holding the weight in set position, a second weight for returning the first-mentioned .weight after releasin the latch, and means element in running position, a weight.

mounted to swing on the same axis as the latch, an arm on the latch arranged to be struck by the weight, means for releasably holding the weight raised durin normal operating conditions, and manna y operabe the armature in comeans on thecontrolling element for releasing the latch.

. 8. A device of the class described comprismg a movable element biased to off position, a ockmg means for holding the element in running position, an armature in the form of a pivoted weight for releasing the locking means, a second weight arranged to drop and restore the first weight to set position, means connected with the element for normally holding the second weight raised, and a COIIllIlOll plvot on which the weights are mounted.

9. A device of the class described comprising a controlling member biased to off position, a locking device controlled by no-voltage or overload conditions and normally holding the member in normal position, means for introducing a time element between each step of the movement of the member from ofl to running position, and an electro-magnetically operated lock-out device for holding the member in ofi position.

10. A device of the class described comprising a controlling lever, a locking means for holding the lever in running position, an electro-magnet controlling the said means, a

lock-out means for the lever held in released leasing the detent, and means controlled by the lever for ener izing said magnet.

12. A device 0 the class described comprising an operating lever, a locking latch for holding the same in running p0s1tion, an electro-magnetically controlled weight for releasing the latch, an electro-magnetically controlled detent for holding the lever in oil position, and means controlled by the lever for releasing said detent.

13. A device of the class described comprising an operating handle, a lock for holding the same in running position, an electromagnet for releasing the lock, a lock for holding the handle in off position and released when current is flowin through the electro-magnet, and a switch or connecting the electro-magnet with the su ply circuit and adapted, to automatically 0 ose during the initial movement of the handle to en'ergize the electro-magnet for releasing the second lock..

14:. An apparatus of the class described comprising a pivoted operating handle, an arcuate arm connected with the handle to move therewith, a pivoted member disposed under the path of the arm, said arm and member having cooperating projections for permitting the handle to be moved step by step in one direction and continuously in the reverse direction, and circuit-controlling means operated by the handle.

15. An apparatus ot the class described comprising a pivoted operating handle, an arcuate arm connected with the handle to move therewith, a pivoted member disposed under the path of the arm, said arm and member having cotiperating projections for permitting the handle to be moved step by step in one direction and continuously in the reverse direction, a locking device for the handle, an element adapted to release the locking device, a weight for returning the element to normal position, and means for raising the weight by the movement of the arm in one direction and released from the arm and moved in the opposite direction to return the said device.

16. An apparatus of the class described comprising an operating handle, separate locking devices for holding the handle in extreme positions, and a controlling means adapted when energized to release one looking device and maintain the other locked.

17. An apparatus of the class described comprising an operating handle, a lock for holding the handle in running position, an electromagnet for releasing the lock under emergency conditions, and manually-actuated means on the handle for releasing the lock independently of the said ineans.

18. An apparatus of the class described comprising an operating handle, a gravitat-- ing latch for holding the same in running position, electricallycontrolled means arranged to impart a hammer blow to the latch for releasing the same, and a manually-controlled device on the handle for releasing the latch independently.

19. An apparatus of the class described comprising a swinging handle, a member connected therewith having a laterally-projected arm, means cooperating with the arm for providing intermittent movement of the handle in one direction, a lock-out device arranged to engage the arm for preventin movement of the handle when the latter is in off position, and means for automatically releasing said lock-out device.

20. An apparatus of the class described comprising an operating handle, an element movable therewith, a switch arranged to be opened by the element when the handle is in off position, an electro-magnet cut into and out of circuit by the switch, a locking device arranged to engage the element and permitting an initial movement of the handle. sufiicient to close the switch, means for cam 41 releasing the device by the electro-magnet, and means cooperating with the element for providing an intermittent movement of the handle.

21. An apparatus of the class described comprising a controlling element biased to return to off position, a locking device for holding the element in. running position, a novoltage release electro-magnet for the said device, a switch for opening the circuit of the electro-magnet, means responsive to overload conditions for opening the switch, a second switch for opening the circuit of the electro-magnet when the element is in ofi' position, and a locking device automatically set when either switch is o ened for preventing the element from eing thrown to running position.

22. an apparatus of the class described comprising an operating handle biased to off position, a no-voltage releasing device for holding the handle in running position and including an electro-magnet, a circuit for the electro-magnet, a normally closed switch in the circuit, an overload electro-magnet for opening the switch, the last-mentioned electro-magnet having an adjustable core for setting the electro-magnet to operate at any predetermined condition, and electro-magnetic locloout device for holding the handle in off position, and a switch controlled by the handle for releasin said device.

23. An apparatus 0' the class described comprising a casing, a contact drum mounted therein, an operating handle, a gearing between the handle and drum, means for returning the handle to off position, a no-voltage release device for holding the handle in running position, and electro-magnetic lockout means for holding the handle in off position, a switch controlled by the handle for releasing such means and contacts bearing on the drum and submerged in an insulating liquid.

24:- The combination of a supporting structure, an operating handle, a contact-carrying drum, and a gear between the drum and handle, a spring tor returning the handle to off position, and a cushioning device arranged in the path of one of the members of the gearing for gradually arresting the movement of the parts.

25. The combination of a casing, a con.- tact-carrying drum mounted in the bottom thereof and adapted to be partially submerged in an insulating liquid, contact fingers bearin on the drum, circuit connec tions contro led by the drum, an oscillatory operating handle, a gearing between the handle and drum for rotating the latter, a spring for returning the handle to off position, a cushioning device arranged in the ath of one of the members of the gearing .or gradually arresting the movement of the parts, a locking device for holding the handle in running position, and means responsive to no-voltage and overload conditions for releasing the said locking device.

26. The combination of a casing composed of a main section and removable bottom and cover sections, a supporting plate on the main section, a contact-carrying element on the main section, means on the main section for operating the element, locking devices for the handle, and means on the support ing plate responsive to no-voltage or overload conditions for controlling the locking devices.

27. The combination of a casing, a contact drum mounted therein, insulating slabs, contact fingers mounted on the slabs for engaging the drum, resistance devices in the casing and connected with the fingers, an operating handle for actuating the drum, a locking device for holding the handle in running position, and means within the casing for releasing the locking device under no-voltage or overload conditions.

28. A device of the class described comprising a controlling handle, means responsive to abnormal conditions for releasably holding the handle in running position, a lock-out means for holding the handle in off position, means for biasing the handle to remain in OK position, a latch for controlling the handle to move step by step and to lock the handle at the end of each step, a switch held open by the handlewhen the latter is in off position, a circuit controlled by the switch for releasing the lock-out means during the initial movement of the handle from off position, and means upon the handle for manually releasing the latch.

29. A motor starter including a controlling device, means adapting the same to be operated by a step by step motion, said means being operable to permit of a continuous reverse motion of said device, means for locking the controlling device in running position, and means operative under abnormal conditions for releasing said lock and returning the handle to 'ofi position.

30. A device of the character described including an operating lever biased to off position, releasable means for holding the handle in running position and responsive to no-voltage or overload conditions, and an electrically controlled lock-out means for preventing movement of the handle from off position in the absence of current in the supply circuit.

31. A device of the character described comprising a controlling lever, means operative to secure a step by step movement of said lever to running position and to permit a continuous reverse motion of said lever to ofi position, means for locking said lever in running position, automatic means for releasing the lever and returning it to off position, and manually controlled means for releasing the lever.

In testimony whereof I afiix my signature in presence of two witnesses.

ANTHONY J. BURNS.

\Vitnesses:

MARTIN MONGAN, JOHN F. BUNDY.

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